Merge branch 'akpm' (patches from Andrew)

Merge more updates from Andrew Morton:

 - a few misc things

 - kexec updates

 - DMA-mapping updates to better support networking DMA operations

 - IPC updates

 - various MM changes to improve DAX fault handling

 - lots of radix-tree changes, mainly to the test suite. All leading up
   to reimplementing the IDA/IDR code to be a wrapper layer over the
   radix-tree. However the final trigger-pulling patch is held off for
   4.11.

* emailed patches from Andrew Morton <akpm@linux-foundation.org>: (114 commits)
  radix tree test suite: delete unused rcupdate.c
  radix tree test suite: add new tag check
  radix-tree: ensure counts are initialised
  radix tree test suite: cache recently freed objects
  radix tree test suite: add some more functionality
  idr: reduce the number of bits per level from 8 to 6
  rxrpc: abstract away knowledge of IDR internals
  tpm: use idr_find(), not idr_find_slowpath()
  idr: add ida_is_empty
  radix tree test suite: check multiorder iteration
  radix-tree: fix replacement for multiorder entries
  radix-tree: add radix_tree_split_preload()
  radix-tree: add radix_tree_split
  radix-tree: add radix_tree_join
  radix-tree: delete radix_tree_range_tag_if_tagged()
  radix-tree: delete radix_tree_locate_item()
  radix-tree: improve multiorder iterators
  btrfs: fix race in btrfs_free_dummy_fs_info()
  radix-tree: improve dump output
  radix-tree: make radix_tree_find_next_bit more useful
  ...

2 files changed, 128 insertions, 19 deletions

diff --git a/usr/Kconfig b/usr/Kconfig
index 572dcf7b6a44..6278f135256d 100644
--- a/usr/Kconfig
+++ b/usr/Kconfig
@@ -98,3 +98,130 @@ config RD_LZ4
 	help
 	  Support loading of a LZ4 encoded initial ramdisk or cpio buffer
 	  If unsure, say N.
+
+choice
+	prompt "Built-in initramfs compression mode"
+	depends on INITRAMFS_SOURCE!=""
+	optional
+	help
+	  This option allows you to decide by which algorithm the builtin
+	  initramfs will be compressed.  Several compression algorithms are
+	  available, which differ in efficiency, compression and
+	  decompression speed.  Compression speed is only relevant
+	  when building a kernel.  Decompression speed is relevant at
+	  each boot. Also the memory usage during decompression may become
+	  relevant on memory constrained systems. This is usually based on the
+	  dictionary size of the algorithm with algorithms like XZ and LZMA
+	  featuring large dictionary sizes.
+
+	  High compression options are mostly useful for users who are
+	  low on RAM, since it reduces the memory consumption during
+	  boot.
+
+	  Keep in mind that your build system needs to provide the appropriate
+	  compression tool to compress the generated initram cpio file for
+	  embedding.
+
+	  If in doubt, select 'None'
+
+config INITRAMFS_COMPRESSION_NONE
+	bool "None"
+	help
+	  Do not compress the built-in initramfs at all. This may sound wasteful
+	  in space, but, you should be aware that the built-in initramfs will be
+	  compressed at a later stage anyways along with the rest of the kernel,
+	  on those architectures that support this. However, not compressing the
+	  initramfs may lead to slightly higher memory consumption during a
+	  short time at boot, while both the cpio image and the unpacked
+	  filesystem image will be present in memory simultaneously
+
+config INITRAMFS_COMPRESSION_GZIP
+	bool "Gzip"
+	depends on RD_GZIP
+	help
+	  Use the old and well tested gzip compression algorithm. Gzip provides
+	  a good balance between compression ratio and decompression speed and
+	  has a reasonable compression speed. It is also more likely to be
+	  supported by your build system as the gzip tool is present by default
+	  on most distros.
+
+config INITRAMFS_COMPRESSION_BZIP2
+	bool "Bzip2"
+	depends on RD_BZIP2
+	help
+	  It's compression ratio and speed is intermediate. Decompression speed
+	  is slowest among the choices. The initramfs size is about 10% smaller
+	  with bzip2, in comparison to gzip. Bzip2 uses a large amount of
+	  memory. For modern kernels you will need at least 8MB RAM or more for
+	  booting.
+
+	  If you choose this, keep in mind that you need to have the bzip2 tool
+	  available to be able to compress the initram.
+
+config INITRAMFS_COMPRESSION_LZMA
+	bool "LZMA"
+	depends on RD_LZMA
+	help
+	  This algorithm's compression ratio is best but has a large dictionary
+	  size which might cause issues in memory constrained systems.
+	  Decompression speed is between the other choices. Compression is
+	  slowest. The initramfs size is about 33% smaller with LZMA in
+	  comparison to gzip.
+
+	  If you choose this, keep in mind that you may need to install the xz
+	  or lzma tools to be able to compress the initram.
+
+config INITRAMFS_COMPRESSION_XZ
+	bool "XZ"
+	depends on RD_XZ
+	help
+	  XZ uses the LZMA2 algorithm and has a large dictionary which may cause
+	  problems on memory constrained systems. The initramfs size is about
+	  30% smaller with XZ in comparison to gzip. Decompression speed is
+	  better than that of bzip2 but worse than gzip and LZO. Compression is
+	  slow.
+
+	  If you choose this, keep in mind that you may need to install the xz
+	  tool to be able to compress the initram.
+
+config INITRAMFS_COMPRESSION_LZO
+	bool "LZO"
+	depends on RD_LZO
+	help
+	  It's compression ratio is the second poorest amongst the choices. The
+	  kernel size is about 10% bigger than gzip. Despite that, it's
+	  decompression speed is the second fastest and it's compression speed
+	  is quite fast too.
+
+	  If you choose this, keep in mind that you may need to install the lzop
+	  tool to be able to compress the initram.
+
+config INITRAMFS_COMPRESSION_LZ4
+	bool "LZ4"
+	depends on RD_LZ4
+	help
+	  It's compression ratio is the poorest amongst the choices. The kernel
+	  size is about 15% bigger than gzip; however its decompression speed
+	  is the fastest.
+
+	  If you choose this, keep in mind that most distros don't provide lz4
+	  by default which could cause a build failure.
+
+endchoice
+
+config INITRAMFS_COMPRESSION
+	string
+	default ""      if INITRAMFS_COMPRESSION_NONE
+	default ".gz"   if INITRAMFS_COMPRESSION_GZIP
+	default ".bz2"  if INITRAMFS_COMPRESSION_BZIP2
+	default ".lzma" if INITRAMFS_COMPRESSION_LZMA
+	default ".xz"   if INITRAMFS_COMPRESSION_XZ
+	default ".lzo"  if INITRAMFS_COMPRESSION_LZO
+	default ".lz4"  if INITRAMFS_COMPRESSION_LZ4
+	default ".gz"   if RD_GZIP
+	default ".lz4"  if RD_LZ4
+	default ".lzo"  if RD_LZO
+	default ".xz"   if RD_XZ
+	default ".lzma" if RD_LZMA
+	default ".bz2"  if RD_BZIP2
+	default ""
diff --git a/usr/Makefile b/usr/Makefile
index e767f019accf..17a513268325 100644
--- a/usr/Makefile
+++ b/usr/Makefile
@@ -5,25 +5,7 @@
 klibcdirs:;
 PHONY += klibcdirs
 
-
-# Bzip2
-suffix_$(CONFIG_RD_BZIP2)  = .bz2
-
-# Lzma
-suffix_$(CONFIG_RD_LZMA)   = .lzma
-
-# XZ
-suffix_$(CONFIG_RD_XZ)     = .xz
-
-# Lzo
-suffix_$(CONFIG_RD_LZO)    = .lzo
-
-# Lz4
-suffix_$(CONFIG_RD_LZ4)    = .lz4
-
-# Gzip
-suffix_$(CONFIG_RD_GZIP)   = .gz
-
+suffix_y = $(CONFIG_INITRAMFS_COMPRESSION)
 AFLAGS_initramfs_data.o += -DINITRAMFS_IMAGE="usr/initramfs_data.cpio$(suffix_y)"
 
 # Generate builtin.o based on initramfs_data.o